Hrm, generally when it’s floating like that and not affecting the landscape, it tends to be either that edit layers are off or the “Affects Landscape” bool on the water component is off.
There was an issue on 5.0 originally that incredibly large landscapes sometimes had problems delegating the brush over many proxies, how large is your landscape and how many heightmap layers does it have currently?
Are you using the landmass plugin? As I’ve seen reports that it’s not compatible with the landscape water system.